The available measurement techniques include at least (a) measurement using overflow tank, (b) measurement using flow meter, and (c) measurement using fixed volume. FIG. 1 shows a schematic view of a structure of measurement using overflow tank. The overflow tank-based measurement includes a pump 11 to transport a liquid in a material tank 12 to a measurement tank 13. When the liquid overflows from an overflow tube 14 of the measurement tank 13, the transportation stops. Then, a valve 15 at the bottom of the measurement tank 13 is opened so that the liquid in the measurement tank 13 flows into a mixer tank 16 to complete the measurement. The structure has the following disadvantages:
1. The overflow-based measurement is not easy to change the measurement volume.
2. During measurement, the liquid material overflows from the overflow tube 14 cannot be easily reclaimed, resulting in waste.
3. After the valve 15 is opened, the liquid can only flow by the gravity. If the liquid has a higher viscosity, the flow speed can be very slow.
4. The liquid in the tube in stationary when not in measurement. If the liquid contains any grounded material, the grounded material may starts to settle at the bottom so that the total organic carbon (TOC) of the de-ionized water (DIW) tube increases.
5. The liquid flows in an open space, which may lead to environmental pollution.
The meter-based measurement includes computing the volume of the liquid by the flow rate and the time, which has the following disadvantages:
1. A system with unsteady flow rate may not be measured correctly, such as, a pump with ON and OFF interval.
2. A system with shared branches causing pressure change will affect the flow rate.
3. A larger tube is required for measuring high flow rate and a smaller is required for measuring low flow rate.
4. The liquid in the tube in stationary when not in measurement. If the liquid contains any grounded material, the grounded material may starts to settle at the bottom so that the total organic carbon (TOC) of the de-ionized water (DIW) tube increases.
5. The residual liquid in the intake tube will affect the measurement accuracy.
The fixed volume-based measurement includes using a dosing pump to transport a fixed volume of liquid through a pistol, which has the following disadvantages:
1. For higher precision, the volume is designed to be small, which amount to about 5lpm. Therefore, this approach is not suitable for measuring a large volume as the precision error will accumulate.
2. The liquid in the tube in stationary when not in measurement. If the liquid contains any grounded material, the grounded material may starts to settle at the bottom so that the total organic carbon (TOC) of the de-ionized water (DIW) tube increases.
3. The residual liquid in the intake tube will affect the measurement accuracy.
To solve the aforementioned disadvantages, it is imperative to devise a syringe meter to address the measurement issues.